1. Technical Field
The present invention relates generally to wireless communication technology, and, more particularly, to a maritime wireless communication method and apparatus that are capable of supporting commercial broadband communication service at sea.
2. Description of the Related Art
Maritime communication is a very old form of communication. Maritime communication is internationally protected because it is closely related to the safety of humans, and it has evolved slower than other communication technologies. However, with the recent rapid advance of communication technology, maritime communication is also in the process of being actively developed.
Maritime communication systems include medium frequency (MF), high frequency (HF) and very high frequency (VHF) band communication equipment and satellite communication equipment in order to perform worldwide maritime communication, and provide voice-oriented communication services with the exception of a simple text transfer service.
A Global Maritime Distress and Safety System (GMDSS) based on a communication system in which pieces of communication equipment having a variety of purposes were integrated with each other was introduced at the end of 1990s. Recently, under the leadership of the International Maritime Organization (IMO), an E-navigation strategy that is intended to collect, integrate, exchange, represent and analyze ship and land-related maritime information using an electronic method, thereby ensuring safety and security at sea and protecting a maritime environment has been discussed with the aim of future enforcement.
Meanwhile, although many ships currently navigate coastal waters, it is difficult for the ships to receive various communication services from land because there is no provision for a maritime broadband digital communication network. Meanwhile, ships on long distance voyages are dependent upon expensive satellite communication.
Furthermore, although various communication means for a GMDSS are installed on a ship, most of them are used for voice communication in an analog form. Some communication devices are capable of digital transmission, but provide service at limited speeds and within very limited areas.
In some countries, maritime digital Very High Frequency (VHF) band communication has been deployed and is being operated on a test basis. However, this is used within very limited areas, and whether it will spread all over the world is not certain. Although ships navigating coastal waters utilize land-based communication networks, such as existing mobile phone networks, the use of the land-based communication networks cannot be fully utilized because the range of communication over the land-based communication networks is limited, and it is difficult for ships that navigate various waters to utilize and communicate over the land-based communication networks.
Meanwhile, the required bandwidth for each ship, exclusive of that for broadcast information, is estimated to be about 100 Kbytes/day based on 2009 estimated figures and to be 10 Mbytes/day based on 2011 estimated figures, and is expected to increase when the e-Navigation era is reached.
Furthermore, in light of the fact that the accidents involving ships mostly occur in coastal waters within 100 km of the coast, various ship safety navigation solutions capable of preventing accidents involving ships have been developed. Wireless communication between ships is required for the safe navigation of the ships. Currently available land-based wireless communications have the disadvantage of short coverage distances. In particular, satellite communication has the disadvantages of low data throughput and high cost.
Korean Patent Application Publication NO. 2011-43963 discloses a maritime communication apparatus and method that perform communication between a base station and a ship using a protocol that is appropriate for distance and signal intensity. However, the technology disclosed in this Korean patent application publication is very limited because it can be applied only to ships that are present within the distance over which radio waves can arrive from land.
Accordingly, there is a need for maritime wireless communication technology that can use a land-based mobile communication network, and can extend land-based wireless communication service to the sea and make the land-based wireless communication service available at sea.